You don't need to logbook a car for sprint.
There is a General Requirement for car and drivers here
https://cams.com.au/regulations/manual/general-requirements
I am pretty sure for sprints any seat is fine provided it's mounted correctly
With tint 'have any window or windscreen fitted made from a material which is clear or, if tinted, compliant with AS 2080;'
If you have a cage it probably wise to register it with CAMS because they do change their cage requirement structure from year to year.

@gav240z This is for you
https://www.domain.com.au/news/hot-property-the-melbourne-fire-station-up-for-sale-812841/?utm_campaign=strap-masthead&amp;utm_source=the-age&amp;utm_medium=link&amp;utm_content=pos1&amp;ref=pos1

it doesn't matter though, James Flett can get plenty power out of these engines.
What we need is more tyre and brake. we run 195/60 tyres whereas the 911 run 225/50 on the rears and the Vette and Pantera even wider tyres.